Index: uspace/lib/c/generic/adt/circ_buf.c
===================================================================
--- uspace/lib/c/generic/adt/circ_buf.c	(revision 7a6065c264dbab78e1758685fd1eda498ab9b73d)
+++ uspace/lib/c/generic/adt/circ_buf.c	(revision 7a6065c264dbab78e1758685fd1eda498ab9b73d)
@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2017 Jiri Svoboda
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libc
+ * @{
+ */
+ 
+/** @file Circular buffer
+ */
+
+#include <adt/circ_buf.h>
+#include <errno.h>
+#include <mem.h>
+#include <stddef.h>
+
+/** Initialize circular buffer.
+ *
+ * @param cbuf Circular buffer
+ * @param buf Buffer for storing data
+ * @param nmemb Number of entries in @a buf
+ * @param size Size of individual buffer entry
+ */
+void circ_buf_init(circ_buf_t *cbuf, void *buf, size_t nmemb, size_t size)
+{
+	cbuf->buf = buf;
+	cbuf->nmemb = nmemb;
+	cbuf->size = size;
+	cbuf->rp = 0;
+	cbuf->wp = 0;
+	cbuf->nused = 0;
+}
+
+/** Return number of free buffer entries.
+ *
+ * @param cbuf Circular buffer
+ * @return Number of free buffer entries
+ */
+size_t circ_buf_nfree(circ_buf_t *cbuf)
+{
+	return cbuf->nmemb - cbuf->nused;
+}
+
+/** Return number of used buffer entries.
+ *
+ * @param cbuf Circular buffer
+ * @return Number of used buffer entries
+ */
+size_t circ_buf_nused(circ_buf_t *cbuf)
+{
+	return cbuf->nused;
+}
+
+/** Push new entry into circular buffer.
+ *
+ * @param cbuf Circular buffer
+ * @param data Pointer to entry data
+ * @return EOK on success, EAGAIN if circular buffer is full
+ */
+int circ_buf_push(circ_buf_t *cbuf, const void *data)
+{
+	if (circ_buf_nfree(cbuf) == 0)
+		return EAGAIN;
+
+	memcpy(cbuf->buf + cbuf->size * cbuf->wp, data, cbuf->size);
+	cbuf->wp = (cbuf->wp + 1) % cbuf->nmemb;
+	cbuf->nused++;
+	return EOK;
+}
+
+/** Pop entry from circular buffer.
+ *
+ * @param cbuf Circular buffer
+ * @param datab Pointer to data buffer for storing entry
+ * @return EOK on success, EAGAIN if circular buffer is full
+ */
+int circ_buf_pop(circ_buf_t *cbuf, void *datab)
+{
+	if (cbuf->nused == 0)
+		return EAGAIN;
+
+	memcpy(datab, cbuf->buf + cbuf->size * cbuf->rp, cbuf->size);
+	cbuf->rp = (cbuf->rp + 1) % cbuf->nmemb;
+	cbuf->nused--;
+	return EOK;
+}
+
+/** @}
+ */